The electronic structure of LaF: A multiconfiguration ligand field calculation

Abstract

A zero-free-parameter ligand field model is used to account for the observed low-lying (E < 10 000 cm-1) electronic states of LaF. The electronic structure of LaF is represented as the effect of a nonpolarizable point F- ligand on the two valence electrons of a free La+ atomic ion. Free-ion configuration interaction (CI) effects (represented by a parametric fit of the free La+ energy levels to Fk,G k Slater-Condon electrostatic and ζ spin-orbit parameters) and ligand-driven CI (treated by B0k ligand field radial integrals evaluated using Hartree-Fock La+ orbitals) are included in the model. A series of calculations is described, from the simplest "primitive LFT model" which includes the three lowest-lying and most important configurations (6s2, 5d 6s, 5d2) to the most elaborate "balanced s-polarized LFT model" which includes six configurations (6s2, 5d 6s, 5d2, 6s6p, 5d 6p, and 6p 2) in order to account properly for s-p polarization effects. The inclusion of ligand-driven CI (metal-centered orbital polarization) effects shows that simple electrostatic atomic-ion-in-molecule models are capable of accounting for the electronic structure of many highly polar diatomic molecules having more than a single metal-centered valence electron. © 1987 American Institute of Physics.